This invention relates to a method of controlling weeds in Japonica rice paddy fields and to herbicidal compositions useful for that purpose.
Rice satisfies the food needs of a large portion of the world's population. The current population explosion and concomitant food shortage underlie the need for improvements in the efficiency of producing rice. One such improvement being sought in an efficient method for controlling weeds in rice paddies.
The compound methyl 2-[((4,6-dimethoxypyrimidin-2-yl)aminocarbonyl)aminosulfonyl]methyl benzoate ##STR1## has been found to be very effective for controlling both annual and perennial paddy field weeds which commonly plague rice paddies. This compound (Compound I) and a method of preparing it are disclosed in European Patent Application No. 81305160.4 (Publication No. 51466, published May 12, 1982). Although the test results in the European Application (Test E) indicate that Compound I (referred to therein as Compound 6) does not cause phytotoxicity to rice, later tests have shown that, although the compound causes little or no phytotoxicity to Indica rice plants, it causes marked phytotoxicity to Japonica rice plants even at low application rates. Thus, even though Compound I was effective in controlling paddy field weeds at very low, environmentally safe application rates, its use as a herbicide in Japonica rice was severely limited.